Timer for internal combustion hammers



' 0% 19395 c L, CHARLES TIMER FOR INTERNAL COMBUSTION HAMMERS Filed Dec.51, 1957 Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE THMER FORINTERNAL COMBUSTION HAMMER/S Delaware Application December 31, 1937,Serial No. 182,867

7 Claims.

This invention relates to internal combustion percussive devices, andmore particularly to ignition apparatus therefor.

One feature of this invention is that it provides means for varying thetime of commencement of ignition; another feature of this invention isthat it provides improved mounting means for the ignition points; stillanother feature of this invention is that the relationship of the pointsmay be readily and conveniently set, without dismantling the ignitionapparatus, to determine the time of initiation of ignition with respectto reciprocation of the piston in the hammer; other features andadvantages of this invention will be apparent from the followingspecification and the drawing, in which:

Fig. 1 is a fragmentary sectional view of the hammer, disclosing theignition timing apparatus in detail; Fig. 2 is an elevation of the timerhousing and mounting; Fig. 3 is a view, partly in section, along theline 3-3 of Fig. 2; Fig. 4 is an elevation of the timer housing andmounting of another modification-of, this invention; Fig. 5 is avertical sectional view along the line 5-5 of.

5 Fig. 4; Fig. 6 is a view along the line 6-6 of Fig. 4, only partlybroken away; and Fig. 7 is a view, partly in section, along the linel-'l of Fig. 5.

The present application is a continuation in part of my previousapplication, Serial No.

135,185 filed April 5, 1937. The ignition apparatus only is illustratedherein. The complete hammer is shown in my previously-mentionedapplication, this hammer being of the same fundamental type as thatshown in Mould Pat- 'ent 1,997,071, or Saunders Patent 1,813,513.

The internal combustion hammer or percussive tool of the type for whichthis ignition apparatus is designed, illustrated more fully in myabove-mentioned application, has a cylinder with a piston hammer freelyreciprocable therein and adapted to impart blows to a tool at t .2bottom of the hammer, being returned after such blow by a piston returnspring assembly. The hammer is provided with a chargaforming devicecomprising a tank for liquid fuel, a carburetor, and the necessarymanifold passages enabling a combustible charge to be delivered to thecombustion chamber above the piston in accordance with known two-cycleengine practice.

' The hammer is provided with an ignition system including aconventional spark plug, and ignition or timing apparatus it. A batteryor other source of current and a buzzer-operated spark coil isconnected, in accordance with known practice, to the timing apparatusand the spark plug. It will be noted that the piston I 1, adapted toreciprocate within the cylinder I0, is provided with a cam surface 22adapted to actuate a cam follower or plunger in the timer 19.

In order to secure eflicient operation of an 5 internal combustionengine it is, of course, necessary to have the high tension spark orignition means initiated at a particular time with respect to thereciprocation of the piston in the cylinder. Too early ignition resultsin knocking, overheat- 10 ing, and other troubles; and too late ignitionresults in poor combustion efficiency, loss of power, slower action ofthe hammer, and the like. The point at which the spark should beinitiated also varies somewhat in accordance with the tempera- 15 tureof the hammer, and it is preferable to provide means for adjusting theaction of the timer in this respect to vary the timing of the ignition.

In the particular timer illustrated in Figs. 1 to 3, the cylinder H! isprovided with an opening 23 2Q therethrough transverse to the axis ofthe cylinder. A sleeve member 24 is held therein by studs 25 tapped intothe cylinder wall or a boss provided therefor. Within the sleeve 24 is alongitudinally movable plunger 25 having a roller 21 25 mounted on apivot shaft ill on the inner end of the plunger 26 adapted to contactthe cam surface 22 on the piston. A coil spring 28, axially disposedwith relation to the plunger, biases or urges it against the piston, sothat reciprocation 30 or movement of. the piston in the cylinder effectslongitudinal movement of the plunger 26. The sleeve 24 is provided witha slot H to permit free movement of the pivot shaft 10, and thus of theplunger 26, with respect to it. 35

The plunger 26 has movably mounted therein and coaxial therewith asecond longitudinally movable plunger 29. The inner end of the plunger29 is provided with a stop 3!] adapted to contact a shoulder on theplunger 26 to prevent 40 outward movement of the second plunger withrespect to the first. A coil spring 3| surrounds the second plunger andlies between a shoulder thereon and a shoulder on the plunger 26,yieldingly urging the second plunger outwardly with 45 respect to thefirst plunger. It will be thus seen that the two plungers may telescopewithin each other to the extent of the space provided between the stop 3and the roller 21, so that the plunger 26 may continue to move outwardlyas a result of movement of the piston even though the second plunger 29has ceased outward movement provided such furthermovement does notexceed the distance between the stop 30 and roller 21. 55

A pair of cooperating ignition points 32 and 33 are provided. The point33 is adjustably mounted on the end of the plunger 29 and adapted to bemoved toward and into contact with the point 32 upon movement of thefirst plunger 26. This point 32 is mounted on a member 34 passingthrough insulated washers 35 and 36 on each side of an opening 31 in thehousing 38. The outer end of the member 34 is threaded, and a nut 39 isprovided for locking the member in place.

The points 32 and 33 are operatively connected in the low tensionignition circuit to control ignition as a result of a change ofrelationship, that is, from open to closed relationship, or vice versa.The point 32 is insulated from the hammer body and connected to the wire2| through the connecting lug 40. The point 33 is grounded to the hammerthrough the plungers in contact with the cylinder wall. It will be notedthat the timing of the hammer may be varied by moving the point 33toward or away from its cooperating point to vary the instant ofinitiation of ignition with respect to movement of the piston. The lug40 engages a flattened portion of the member 34 and acts as a wrench forholding the member while the nut 39 is drawn up tight. It is preventedfrom falling out of place when the nut is slightly loosened by theshoulder portions engaging the washer.

The slot 1| is, of course, deeper than the amount of movement of thepivot shaft 10 as a result of the effect of the cam surface on theroller 2'! during reciprocation of the piston. Outward movement of theroller, pivot shaft, and plunger 26 carries the second plunger 29 alonguntil the point 33 contacts the fixed point 32. Contact of these twopoints stops further outward movement of. the plunger 29; but it doesnot stop further outward movement of the plunger 26 under the influenceof further movement of the cam surface with respect to the roller 21,since the plunger 29 is adapted to telescope further within the plunger26 against the bias of the spring 3|. That is, the two plungers maintainthe relation illustrated during movement until the points contact eachother; and further movement of the plunger 26 is thereafter permitted bya change in relationship between the two plungers.

The springs providing the necessary bias on the two plungers are hereshown as nested coil springs in substantially coaxial relationship. Thespring 3| is of lighter construction than 28, so that during the latterpart of the movement, when the plunger 26 is pushing against bothsprings, there will not be undue wear on the cam surface. The particulararrangement shown has been found to be very rugged as well as efiicient.The plungers and springs are so arranged that the terrific vibration ofthe hammer when in operation causes little or no wear and difficultywith the parts. The springs particularly have been found to stand upmuch better than flat springs of various types originally used in thehammers.

Shims may be inserted between the outer or plate portion of the member24 and the wall of the cylinder, so that when the studs 25 are drawn upthe final position of the cam follower with respect to the piston andcam surface thereon will be affected thereby. The presence of theseshims serves two purposes. They might be inserted or removed to changethe initiation point, to compensate for wear of the cam surface or camfollower, or both. Adjustment here also assures the minimum over travelof the point 33 necessary to avoid intermittent separation of the pointfrom vibration and spring surge during the period it is desired to havethem stay closed. That is, if the points just barely touch and then stayin that position for an appreciable time interval, surges in the springs28 and 3|, vibrations in the body of. the hammer, or both, may cause thepoints to separate momentarily and thus interrupt ignition. Where thereis considerable overtravel of the first plunger 28 the spring 3| is putunder sufficient tension to insure that the points 32 and 33 remain incontact during the interval that contact is desired. In the particularembodiment of this invention illustrated in Fig. l, for example, thereis about forty-seven thousandths of an inch difference between the lowpoint and the high point on the cam surface of the piston, so that theplunger 26 moves about this distance during reciprocation of the piston.The points are preferably set with an initial gap of only about fivethousandths of an inch, so that there is thus about forty-twothousandths of an inch overtravel to insure maintenance of the pointsclosed.

In order to facilitate original adjustment of the shims in the shop orin the field, the outer face 8| of the plunger 26 is arranged to beabout forty-five thousandths of an inch from the outer face 82 of theflat portion of the member 24 when the member 26 abuts the shoulder 83.In order to insure proper initial position of the plunger and pointswith respect to the piston it is then only necessary to bring the highpoint of the cam surface on the piston adjacent the roller 21, so thatthe plunger 26 is moved as far to the left as it would be in operation,and then to insert or remove shims beneath the fiat portion of themember 24 until the outer surface 8| of the plunger 26 is flush with thesurface 82. This makes a very convenient assembly or field adjustment,and one which is independent of wear on the cam surface or roller.

The housing 38 is so constructed and arranged as to seal the points fromatmosphere. This is a desirable feature, since it prevents any chance ofa sparking at the points igniting combustible vapors which may bepresent in the air about the hammer. The tank in the charge formingdevice contains a supply of relatively volatile inflammable fluid,usually gasoline, which fluid is open to atmosphere through the tankfiller cap, the air intake to the carburetor, and the like. Portions ofunburned charge are frequently exhausted from the cylinder, moreover,through the exhaust port. Priming of the hammer when it is cold in orderto facilitate starting also increases the gasoline vapors present in theatmosphere immediately about the hammer. When these hammers are usednear gas mains, in mines, or the like, combustible vapors or gases maybe present which are of an even more explosive nature. Enclosing thepoints in a housing which seals them from atmosphere, therefore, is asafety feature tending to prevent undesired ignition of. these vapors.

Another modification of this invention is illustrated in Figs. 4 to 7.While this is generally analogous to the modification shown in Figs. 1to 3, and just described, it differs therefrom in several importantrespects. In the modification now being discussed the cylinder wall hasa cylindrical bearing portion 43 mounted therein and fastened by anyconvenient means, as by the bolts 47. This bearing member 46 comprises asolid cylindrical portion received within the cylinder, and a splitsleeve portion on the exterior, or end farthest from the cylinder 45.This split portion comprises two halves 48 and 49, adapted to be drawntogether by any convenient means, as the studs 50.

The member 46 has mounted therein, in the portion within the cylinder, aplunger adapted to be longitudinally moved as a result of contact of theroller 52 with the cam surface on the piston 53, the roller beingmounted on a pivot shaft 72 rotatably mounted in the end of the plunger5! and movable in the slot 13. This plunger has mounted therewithin, andlongitudinally movable with respect thereto, a second plunger 54. Coilspring 55 urges the plunger 5i against the cam surface on the piston;and coil spring 56 urges the second plunger outwardly. This plunger, asin the previous timer, carries a contact point 51.

The other contact point 58 is carried by a housing member 59, thismember being here shown as substantially cylindrical in shape and ashaving an opening 69 therethrough, so placed that the points are visibletherethrough. As in the preceding modification, outward movement of. the

plunger 5! as a result of the effect of the cam surface on the roller 52carries the plunger 54 along until engagement of the points 5'! and 58;and thereafter further outward movement of the plunger 5! is permittedby telescoping movement of the plunger 54 within the plunger 5|.

The point 58 is fixedly mounted in the member 59, but this latter memberis slidably mounted within the split sleeve bearing formed by the twoparts 48 and 49. These parts are so arranged that, when the studs 50 areloosened, the member 59 may be moved toward or away from the hammer, andthus the point 58 is adjusted with respect to the point 51, so that thetime of change of relationship of the points with respect toreciprocation of the piston may be set as desired. This desired settingmay be determined by running the hammer, or by setting the pistontherein at a predetermined position and then spacing the point 58 apredetermined distance from the point 51. The provision of the opening63 enables a gauge to be inserted, if. desired, to set the points aspecific distance apart at a given setting of the piston. When thedesired setting has been secured it is only necessary to draw up thestuds 50 to lock the member 59 in place.

It is thus apparent that a very convenient and ready means of settingthe timing of hammers of this type is secured. The apparatus is suchthat the timing may be readily set on the job, with any standard wrenchwhich will actuate the studs 55; and the fact that the studs may becaused to give any desired frictional grip on the member 59 enables itto be worked in, by hand, only a thousandth of an inch or so at a time.

While I have shown and described certain embodiments of my invention, itis to be understood that it is capable of many modifications. Changes,therefore, in the construction and arrangement may be made withoutdeparting from the spirit and scope of the invention as disclosed in theappended claims, in which it is my intention to claim all noveltyinherent in my invention as broadly as permissible, in view of the priorart.

I claim:

1. Ignition apparatus for an internal combustion percussive hammerhaving a cylinder, a piston freely reciprocable therein, said pistonbeing adapted to impart impacts to a tool, and means for supplying saidcylinder with a combustible charge, including: an ignition system forigniting said charge, said system including a pair of cooperatingignition points for controlling said ignition upon a change ofrelationship thereof, at least one of said points being movable; alongitudinally movable plunger actuated by reciprocation of said piston;and means on said plunger longitudinally movable with respect theretoand carrying one of said points, whereby said plunger is effective tomove said one point toward the other and to continue further movementafter said points have come into contact.

2. Apparatus of the character claimed in claim 1, wherein said lastmentioned means comprises a member slidably mounted in said plunger anda coil spring biasing said member with respect thereto.

3. Ignition appartus for an internal combustion percussive hammer havinga cylinder, a piston freely reciprocable therein, said piston beingadapted to impart impacts to a tool, and means for supplying saidcylinder with a combustible charge, including: an ignition system forigniting said charge, said system including a pair of cooperatingignition points for controlling said ignition upon a change ofrelationship thereof; a longitudinally movable plunger actuated byreciprocation of said piston through contact with a cam surface thereon,said plunger being biased against said surface by a coil spring; asecond longitudinally movable plunger slidably mounted in said firstplunger, said second plunger carrying one of said points, whereby saidfirst plunger is effective to move said point toward the other; meanscarried by said cylinder on which said other point is mounted, saidmeans permitting adjustment of the position of said other point to varythe timing; and a coil spring between said two plungers, whereby furthermovement of said first plunger is permitted after said points have comeinto contact.

4. Ignition apparatus for an internal combustion percussive hammerhaving a piston reciprocable therein, including: a pair of cooperatingignition points having operative connections for controlling ignitioncurrent, at least one of said points being movable; actuating means insaid hammer for moving one of said points toward and away from saidother point in accordance with the reciprocation of said piston in saidhammer, whereby said points are adapted to be in closed or separatedrelationship; and relatively large and heavy means carrying the other ofsaid points, said means being readily adjustable with respect to saidhammer for varying the time of change of relationship of said pointswith re spect to reciprocation of said piston.

5. Ignition apparatus for an internal combustion percussive hammerhaving a piston reciprocable therein, including: a pair of cooperatingignition points having operative connections for controlling ignitioncurrent, at least one of said points being movable; actuating means insaid hammer for moving one of said points toward and away from saidother point in accordance with the reciprocation of said piston in saidhammer, whereby said points are adapted to be in closed or separatedrelationship; a relatively large and heavy member carrying the other ofsaid points; and means on the hammer in which said carrying member isslidably mounted for movement toward and away from said hammer,

whereby one of said points may be adjusted with respect to the other forvarying the time of change of relationship of said points with respectto reciprocation of said piston.

6. Apparatus of the character claimed in claim 5, including means forlocking said carrying member in a desired position in said mountingmeans.

7. Ignition apparatus for an internal combustion percussive hammerhaving a cylinder, a piston freely reciprocable therein, said pistonbeing adapted to impart impacts to a, tool, and means for supplying saidcylinder with a combustible charge including: an ignition system forigniting said charge, said system including a pair of cooperatingignition points for controlling said ignition upon a change ofrelationship thereof, at least one of said points being movable; alongitudinally movable plunger actuated by reciprocation of said piston;means on said plunger l0ngitudinally movable with respect thereto andcarrying one of said points, whereby said plunger is effective to movesaid one point toward the other and to continue further movement aftersaid points have come into contact; a member carrying the other of saidpoints; a split sleeve on the hammer, said carrying member being mountedtherein for slidable movement toward and away from said hammer, wherebythe position of the point carried by said member may be adjusted withrespect to the other point for varying the time of change ofrelationship of said points with respect to reciprocation of saidpiston; and means for contracting said sleeve to lock said memberagainst movement therein.

CARL L. CHARLES.

